Prolactin release

No effect on prolactin release in normal subjects, but diminishes increased prolactin levels in acromegaly... 

Takahara J, Yunoki S, Yakushiji W, et ah Stimulatory effects of gamma-hydroxybutyric acid on growth hormone and prolactin release in humans. J Clin Endocrinol Metab 44 1014-1017, 1977... 

A further totally separate DA pathway arises from A12 in the arcuate nucleus and forms the tuberoinfundibular tract in the median eminence to the pituitary gland for controlling prolactin release. This is partly achieved by DA being released into capillaries of the hypothalamic-hypophyseal portal system and then inhibiting the prolactin releasing cells (lactotrophs) of the anterior pituitary. 

When tested on prolactin release in isolated mammatrophs of bovine anterior pituitary, apomorphine appeared a full agonist (inhibiting release) while antagonism of the inhibition of prolactin release by the neuroleptics showed a potency more similar to that for binding than for blocking cAMP production. Also the inhibition of prolactin... 

Control (inhibition) of prolactin release Tuberoinfundibular tract from A12 in the arcuate nucleus of the median eminence to pituitary Humans Hypoprolactaemia Humans Hyperprolactaemia Galactorrhoea Amenorrhoea D2 ... 

DA antagonists are anti-emetic, elevate plasma prolactin and have major motor and behavioural effects. Thus DA must be involved in the initiation of vomiting, the secretion of prolactin and control of motor and behavioural activity. Its role in emesis and as the prolactin release inhibitory factor have been adequately covered above. Its motor and behavioural function will now be considered. 

In addition to the classical stress hormones already reviewed, several other hormones are augmented in response to stress. Stress-induced prolactin release is one of the most frequently studied examples. There is no doubt about the causal relationship between stress and increased pituitary prolactin release, but the biological meaning is much less clear (G2). This phylogenetically old hormone has been shown to have more than 85 different functions in all vertebrate species. However, besides its role in the induction of maternal lactogenesis, the physiological importance of prolactin is at present not fully established. Experimental and clinical evidence supports the view that prolactin is also an immunoregulating hormone (M44, R18). Prolactin receptors are present on human T and B lymphocytes (R18), and T lymphocytes depend on prolactin for maintenance of immunocompetence (B19). In addition, it has been shown that prolactin is able to influence the devel-... 

The release of prolactin from the adenohypophysis is normally inhibited by prolactin-inhibiting hormone (PIH, dopamine) from the hypothalamus. Prolactin secretion is also controlled by prolactin-releasing factor (PRF). The release of PRF from the hypothalamus is mediated by reflexes elicited by suckling and breast stimulation. 

Use in combination with lithium or valproate for the acute treatment of mania or mixed states Antagonist of postsynaptic DA2 receptors atypical agents also block 5-HT2a receptors that increase the presynaptic release of DA thus lowering the risk of extrapyramidal symptoms and prolactin release... 

Dopamine A few studies have examined the dopaminergic effects of LSD. The affinity of LSD for D2 receptors is similar to its affinity for 5-HT2 sites, and it has a slightly lower affininty for D1 receptors (Watts et al. 1995). LSD has partial agonist effects at D2 receptors as seen in the inhibition of prolactin release (Giacomelli et al. 1998). Neuroleptic drugs are also used clinically to terminate an LSD experience. Thus, the effects of LSD on dopaminergic function may contribute to its hallucinogeinc effects. 

The DA receptor regulating prolactin release in the pituitary is of the D2 " type [50]. This view is substantiated by the studies of Carlsson and coworkers, who reported that prolactin release response is different in male and female rats given partial DA agonists of different intrinsic efficacy [13]. In these studies, endogenous DA was depleated and prolactin levels were... 

Dopamine A. As the precursor of norepinephrine and epinephrine (p. 184), dopamine is found in sympathetic (adrenergic) neurons and adrenomedullary cells. In the CNS, dopamine itself serves as a neuromediator and is implicated in neostriatal motor programming (p. 188), the elicitation of emesis at the level of the area postrema (p. 330), and inhibition of prolactin release from the anterior pituitary (p. 242). 

The dopamine D2 agonists bromocriptine and cabergoline (pp. 114, 188) inhibit prolactin-releasing AH cells (indications suppression of lactation, prolactin-producing tumors). Excessive, but not normal, growth hormone release can also be inhibited (indication acromegaly) (3). 

As already stated, the principal advantage of the mouse is that it provides an alternative rodent species recognized by regulatory authorities. This has proved helpful for compounds such as dopamine agonists that can reduce prolactin release, the hormone essential for the establishment and maintenance of early pregnancy in the rat. 

POMC peptides derived from rat pituitary extracts prolactin-releasing peptides in the bovine hypothalamic extract pseudechetoxin, a peptide blocker of cyclic nucleotide-gated ion channels pseudo-peptide analogues of thiol proteinase inhibitors relaxin-like molecule from the male atlantic stingray, Dasyatis sabina... 

Prolactin. Prolactin is one of several hormones released following seizures. The magnitude of prolactin release has been shown to be greater with bilateral ECT than with unilateral ECT (Lisanby et al. 1998 Swartz and Abrams 1984) and with higher-intensity stimulation than with low-intensity stimulation (Lisanby et al. 1998 Robin et al. 1985 Zis et al. 1993). Despite these clear associations, the prolactin rise with ECT has not proven to be a marker of clinical improvement (Lisanby et al. 1998), although C. P. Clark et al. (1995) reported a trend association between percentage of prolactin increase following the first ECT and lower depression scores at the end of the ECT course. 

McCance SL, Cohen PR, Cowen PJ Dthium increases 5-HT-mediated prolactin release. Psychopharmacology 99 276-281, 1989 McCann U, Hatzidimitriou G, Ridenour A, et al Dexfenfluramine and serotonin neurotoxicity further prechnical evidence that chnical caution is indicated. J Pharmacol Exp Ther 269 792-798, 1994 McCarley RW REM sleep and depression common neurobiological control mechanisms. Am J Psychiatry 139 565-570, 1982 McCarley RW, Hobson JA Neuronal excitability modulation over the sleep cycle a structural and mathematical model. Science 189 58-60, 1975... 

Zis AP, Grof P, Webster M, et al The cyclicity of affective disorders and its modifications by drugs. Psychopharmacol Bull 16 47-49, 1980 Zis AP, McGarvey KA, Clark CM, et al Effect of stimulus energy on electroconvulsive therapy-induced prolactin release. Convulsive Therapy 9 23-27, 1993... 

Endocrine system Dopamine inhibits prolactin release in human being. It also acts on somatotrophs to increase growth hormone release. 

No preparation of prolactin is available for use in prolactin-deficient patients. For patients with symptomatic hyperprolactinemia, inhibition of prolactin secretion can be achieved with dopamine agonists, which act in the pituitary to inhibit prolactin release. 

Dopamine agonists suppress prolactin release very effectively in patients with hyperprolactinemia. GH release is reduced in patients with acromegaly, although not as effectively. Cabergoline and bromocriptine are also used in Parkinson s disease to improve motor function and reduce levodopa requirements (see Chapter 28). Newer, nonergot D2 agonists... 

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